Upcycling of Waste PVC into CaCO₃/KOH-Modified Porous Carbon for Supercapacitor Applications

This study introduces a green method for converting waste polyvinyl chloride (PVC) into hierarchical porous carbon materials. By using CaCO₃ pre-activation to capture HCl and form meso/macroporous frameworks, followed by KOH activation to tune microporosity, high-surface-area porous carbon was successfully produced. The effects of KOH loading ratios (C-PVC:KOH = 1:1 to 1:3) on the primary activated carbon material were systematically investigated. It was found that a ratio of 1:2 (C-KOH-2) yielded optimal material properties, with a specific surface area of 1729 m² g^-1 and an oxygen doping content of 7.37%. Electrochemical measurements revealed that C-KOH-2 exhibited a high specific capacitance of 360.4 F g^-1 at 1 A g^-1, retaining 72.1% of its capacitance at 10 A g^-1. The symmetric supercapacitors achieved an energy density of 9.9 Wh kg^-1 at 125 W kg^-1, with 93.12% capacitance retention over 5000 cycles. This dual-purpose approach enables the upcycling of PVC waste while promoting the development of high-performance electrodes.